The embodiment relates to an electromagnetic switching device.
An electromagnetic switching device is a kind of an electrical contact switching device for supplying or shutting off current, and may be used for various industrial equipments, machines or vehicles.
Hereinafter, an electromagnetic switching device according to the related art will be described with reference to accompanying drawings.
FIG. 1 is a sectional view showing an electromagnetic switching device which is in a power-off state according to the related art. FIG. 2 is a sectional view showing an electromagnetic switching device which is in a power-on state according to the related art.
Referring to FIGS. 1 and 2, the electromagnetic switching device 1 according to the related art includes a frame 20, a fixed contact point 21 fixed to the frame 20, a movable contact point 40 which can make contact with and can be separated from the fixed contact point 21, and an electric actuator 30 which drives the movable contact point 40.
The electric actuator 30 may include a coil 31 for generating electromagnetic force, a fixed core 32 fixed in the coil 31, a movable core 33 movable closely to or away from the fixed core 32, a shaft 34 having one end connected to the movable core 33 and the opposite end connected to the movable contact point 40, and a return spring 35 for applying elastic force to the movable core 33 in order to allow the movable core 33 to be spaced apart from the fixed core 32.
A wipe spring 50, which applies an elastic force to the movable contact point 40 to allow the movable contact point 40 to make contact with the fixed contact point 21, may be provided at the one end of the shaft 34. A spring support part 341, which makes contact with the wipe spring 50 to support the wipe spring 50, may be provided to the shaft 34. A stopper 321, which makes contact with the spring support part 341 to limit the movement of the shaft 34, may be provided to the fixed core 32.
According to the configuration described above, when supplying electric power, the electric power is applied to the coil 31 so that an electromagnetic force is generated near the coil 31. Thus, the movable core 33 moves closely to the fixed core 32, so that the movable contact point 40 makes contact with the fixed contact point 21.
Meanwhile, when the electric power is shut off, the supply of the electric power to the coil 31 is shut off, so that the movable core 33 returns to the initial position by the elastic force of the return spring 35. Thus, the movable contact point 40 is separated from the fixed contact point 21 so that the electric power is shut off.
A process of fabricating the electromagnetic switching device mainly includes three steps.
The first step is a process of fabricating a shaft assembly. After the shaft 34, the movable core 33, the fixed core 32 and the plate 60, which are components necessary for fabricating the shaft assembly, are stacked, a lower end portion of the shaft 34 is completely fixed to the movable core 33 through a laser welding scheme.
The second step is a process of fabricating a mechanism assembly. The concerned components (such as a coil, a yoke 70 or a frame) are stacked and combined at an upper side or lower side of the shaft assembly fabricated in the first step. Since the combination is an irreversible process, if a malfunction is found after the combination, the entire mechanism assembly must be scraped.
The third step is a final assembling step of completing the electromagnetic switching device.
The case 10 is coupled with the mechanism assembly assembled in the first and second steps. Since a structure for fixing the two components after finishing the coupling does not exist, the two components are coupled by coating epoxy on a coupling portion. If the finished product is completed, a basic property test for the product is performed. If a malfunction is found from the finished product in the test, the finished product is discarded.
As described above, the electromagnetic switching device according to the related art has a problem in that great mutual dependence exists between the components. That is, in the processes of performing each step, a next process is performed by coupling an additional component with the assembly fabricated in a previous process. Thus, since each component is completely coupled, when a failure is found from some components after finishing the assembling work, the entire assembly or finished product must be discarded. Further, because of the sequential fabricating process, if a problem is caused in one of the entire processes, the entire processes for producing the finished product may be delayed.